This invention relates to manufacturing processes and more specifically to a process for introducing one or more components into a manufacturing process using a recirculation loop.
The main goal of a polyester manufacturing process is, of course, to completely or as near as completely as possible, react or convert the dicarboxylic acid in the reactor to monomer, oligomer, and ultimately into a polymer. It is also commonly known that a continuous feeding of solid diacid reactant directly into a hot reaction mixture may give rise to the solid reactant becoming tacky on account of dihydroxy vapors condensing on the surface of the relatively cold diacid, thus inhibiting efficient polyester formation. Therefore, in an effort to maintain the goal of highest efficiency, conventional polyester processes often utilize large paste tanks for premixing solid dicarboxylic acid reactants before introducing them into a reactor. For example, U.S. Pat. No. 3,644,483 discloses such use of paste tank addition.
While effective, the necessity for a paste tank does increase the costs as well as the amount of space needed to properly install and operate a polyester manufacturing facility. Furthermore, as the business of manufacturing polyesters becomes more competitive, alternative lower cost manufacturing processes and apparatuses have become highly desirable. A variety of processes and apparatus have been developed, however, these systems still contain relatively complex, costly designs that cannot be built or installed quickly. These designs also typically require more costly expertise to properly maintain and operate.
Therefore, the need still exists for a more compact, efficient and cost effective method for introducing reactants, such as terephthalic acid and other solid dicarboxylic acid reactants, into a polyester reaction mixture.
The present invention therefore provides a process for introducing one or more components into a reaction fluid and/or process fluid of a manufacturing process. More specifically, the process of the present invention pertains to the use of a recirculation loop in connection with a manufacturing process.
In a first aspect, the present invention provides a process for introducing a component into a process fluid comprising the steps of: (a) providing a recirculation loop having an influent and an effluent wherein the influent is in fluid communication with a process fluid; (b) recirculating at least a portion of the process fluid of step (a) through the recirculation loop wherein the process fluid flowing through the recirculation loop is a recirculation fluid; (c) decreasing the pressure of the recirculation fluid of step (b) with at least one pressure decreasing device at at least one point in the recirculation loop; and (d) feeding a component into the recirculation loop adjacent to or at the pressure decreasing device of step (c), to thereby introduce a component into the process fluid.
In a second aspect, the present invention provides a process for introducing a solid polyester precursor reactant into a reaction mixture comprising the steps of: (a) providing a reactor configured to define an internal volume wherein at least a portion of the internal volume is occupied by a reaction mixture comprising a first polyester reactant and a polyester reaction product; (b) providing a recirculation loop having an influent and an effluent wherein the influent is in fluid communication with the internal volume of the reactor; (c) recirculating at least a portion of the reaction mixture through the recirculation loop wherein the first polyester reactant and polyester reaction product flowing through the recirculation loop are recirculation fluids; and (d) feeding a second polyester reactant into the recirculation loop, wherein the second polyester reactant is the solid polyester precursor reactant, to thereby introduce solid polyester precursor reactant into the reaction mixture.
In still a third aspect, the present invention provides a process for introducing a solid polyester precursor reactant into a reaction mixture comprising the steps of: (a) providing a reactor configured to define an internal volume wherein at least a portion of the internal volume is occupied by a reaction mixture comprising a first polyester reactant and a polyester reaction product; (b) providing a recirculation loop having an influent and an effluent wherein the influent is in fluid communication with the internal volume of the reactor; (c) recirculating at least a portion of the reaction mixture through the recirculation loop wherein the first polyester reactant and polyester reaction product flowing through the recirculation loop are recirculation fluids; (d) decreasing the pressure of the recirculation fluids with at least one pressure decreasing device at at least one point in the recirculation loop; and (e) feeding a second polyester reactant into the recirculation loop adjacent to or at the pressure decreasing device, wherein the second polyester reactant is the solid polyester precursor reactant, to thereby introduce solid polyester precursor reactant into the reaction mixture.
Additional advantages and embodiments of the invention will be obvious from the description, or may be learned by practice of the invention. Further advantages of the invention will also be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. Thus, it is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory of certain embodiments of the invention and are not restrictive of the invention as claimed.